The various stages through which an enterprise bean go
through its lifetime is known as the life cycle of EJB. Each type of enterprise
bean has different life cycle. Here we are telling you about the lifecycle of
message driven bean. This type of bean follow three steps:
1)setMessageDrivenContext:-This method is used
to pass the context object to the instance.
2)ejbCreate:-This method is generated automatically whenever a new
enterprise bean is created.
3)ejbRemove:-At this stage the bean instance is ready to move for the
garbage collection.
em.persist(newsEntity):-This method makes an entity instance that is
managed and persistence.
em.merge(newsEntity):-By using this method we can merge the state of the given entity into the current persistence context.
em.remove(em.merge(newsEntity)):-This method is used for removing
the entity instance.
Here is the program denoting life cycle of message
driven bean.
package ejb;
import java.util.List;
import javax.ejb.Stateless;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
@Stateless
public class NewsEntityFacade implements NewsEntityFacadeLocal {
@PersistenceContext
private EntityManager em;
public void create(NewsEntity newsEntity) {
em.persist(newsEntity);
}
public void edit(NewsEntity newsEntity) {
em.merge(newsEntity);
}
public void remove(NewsEntity newsEntity) {
em.remove(em.merge(newsEntity));
}
} |
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